Weakness and fatigue are common complaints with a variety of causes, so it is not surprising that the diagnosis of MG is often missed in people when the weakness is mild or restricted to only a few muscles. Once the possibility occurs to a physician, however, there are three general approaches to confirming the diagnosis.
Pharmacological confirmation involves use of drugs that worsen or improve the muscle weakness associated with MG. When injected, a drug called Tensilon (edrophonium chloride) can reverse myasthenic symptoms for several minutes. Patients may also be instructed to take a small amount of a longer-acting medication called Mestinon (pyridostigmine bromide) after meals at home to assess its response over several days.